A Numerical Analysis on Different Types of Solar Air Heaters
Bibhuti Bhusan Nayak*
Mechanical Engineering Department, National Institute of Technology Sikkim, India
*Corresponding Author: Bibhuti Bhusan Nayak, National Institute of Technology Sikkim, Department of Mechanical Engineering, Ravangla, Sikkim, India.
Published: January 08, 2025
Abstract
Solar air heater is a type of heat exchanger which transforms solar radiation into heat energy. The thermal performance of conventional solar air heater has been found to be poor because of the low convective heat transfer coefficient from the absorber plate to the air. Use of artificial roughness on surface is effective way to break laminar boundary sub layer. It enhances rate of heat transfer from absorber plate to flow of air stream. An attempt has been made to carry out CFD based analysis using Fluent to fluid flow and heat transfer characteristics of solar air heater. Model of solar air heater involving air inlet, absorber plate, glass, and solar air heater with baffles was modelled by ANSYS Workbench and the results were obtained by using ANSYS FLUENT software. It is evident from the simulation that solar air heater with fins increases the heat transfer area and also help in creating turbulence which in turn increases the temperature of the air. Use of polyethylene (green house plastic) as a glazing material for solar air heater is a great choice because though it collects 5% less solar irradiation from the sun but it traps the heat for longer time, acts as an insulating material. As they form a bond with water to assist evaporation by absorption of broadband light, they are utilized as good solar thermal absorber materials. During the study, the heat carrier's maximum temperature reached 48˚C at a solar radiation intensity 9 W/m2 and an ambient air temperature of about 30˚C. Also, it has been observed that the solar radiation intensity and the outlet air temperature increases from 10 AM to 2.00 PM of the day as the intensity of solar radiation at Gangtok used in the study is maximum up to 2.00 PM and then it decreases.
Keywords: Solar air heater; Solar Energy; CFD; Heat transfer; Baffles and fins; Temperature distribution
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